1. Field of the Invention
The invention relates to a caliper brake mechanism of compact design capable of generating high braking force, and can be particularly adapted to accomodate limited lateral movements of the surfaces to be braked.
2. Prior Art
Prior art brakes for providing large braking forces generally require relatively long caliper arms and large actuators to generate sufficient braking force, which arms require sufficient space to accomodate the correspondingly longer travel. Commonly this space is not easily provided and the design might be compromised with resulting marginal braking capacity.
Also, caliper brakes have been used for many years to brake discs which can be machined and journalled within relatively close tolerances so that, when the disc rotates, braking surfaces of the disc are maintained within reasonable limits of ideal or theoretical braking surface planes. When used with such discs, brake shoes of the calipers can be adjusted to a close spacing from the disc for improved braking performance. In some applications caliper brakes have also been used to brake or clamp on other items, for example as a rail clamp particularly for use with a mobile crane. In this application difficulties arise because rails carrying the crane usually cannot be held to such close dimensional limits as discs, and thus braking surfaces of the rails exhibit a considerable deviation from ideal braking surface planes. Consequently, a caliper brake that is adapted to clamp directly onto a rail must be able to accommodate lateral deviations of the braking surfaces otherwise one or both of the shoes likely will intermittently contact the rail thus causing premature shoe wear. Alternatively the brake shoes could be adapted for relatively long travel before contacting the braking surface so that when retracted the shoes are disposed so as not to interfere with the rail as the crane is traversed along the rails. If the caliper brake provides long travel of the shoes from a retracted position, usually considerable caliper arm movement is required and this requires considerable clearance or space adjacent the caliper brake unit, which space is not always available where required.